dt-bindings: display: eliminate yamllint warnings

Eliminate the following yamllint warnings:
./Documentation/devicetree/bindings/display/bridge/analogix,anx7625.yaml
:52:9: [warning] wrong indentation: expected 6 but found 8 (indentation)

./Documentation/devicetree/bindings/display/bridge/intel,keembay-dsi.yaml
:42:8: [warning] wrong indentation: expected 8 but found 7 (indentation)
:45:8: [warning] wrong indentation: expected 8 but found 7 (indentation)

./Documentation/devicetree/bindings/display/intel,keembay-msscam.yaml
:21:6: [warning] wrong indentation: expected 6 but found 5 (indentation)

./Documentation/devicetree/bindings/display/panel/novatek,nt36672a.yaml
:25:10: [warning] wrong indentation: expected 10 but found 9 (indentation)

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201207044830.1551-2-thunder.leizhen@huawei.com
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/display/bridge/analogix,anx7625.yaml

@@ -49,8 +49,8 @@ properties:
           Video port for panel or connector.
 
     required:
-        - port@0
-        - port@1
+      - port@0
+      - port@1
 
 required:
   - compatible

Documentation/devicetree/bindings/display/bridge/intel,keembay-dsi.yaml

@@ -39,10 +39,10 @@ properties:
 
     properties:
       '#address-cells':
-       const: 1
+        const: 1
 
       '#size-cells':
-       const: 0
+        const: 0
 
       port@0:
         type: object

Documentation/devicetree/bindings/display/intel,keembay-msscam.yaml

@@ -18,8 +18,8 @@ description: |
 properties:
   compatible:
     items:
-     - const: intel,keembay-msscam
-     - const: syscon
+      - const: intel,keembay-msscam
+      - const: syscon
 
   reg:
     maxItems: 1

Documentation/devicetree/bindings/display/panel/novatek,nt36672a.yaml

@@ -22,7 +22,7 @@ properties:
   compatible:
     items:
       - enum:
-         - tianma,fhd-video
+          - tianma,fhd-video
       - const: novatek,nt36672a
     description: This indicates the panel manufacturer of the panel that is
       in turn using the NT36672A panel driver. This compatible string